Chapter 13. Memory, Learning, and Development
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By Emily Underwood Nestled deep within a brain region that processes memory is a sliver of tissue that continually sprouts brand-new neurons, at least into late adulthood. A study in mice now provides the first glimpse at how these newborn neurons behave in animals as they learn, and hints at the purpose of the new arrivals: to keep closely-related but separate memories distinct. A number of previous studies have suggested that the birth of new neurons is key to memory formation. In particular, scientists believe the new cell production—known as neurogenesis—plays a role in pattern separation, the ability to discriminate between similar experiences, events, or contexts based on sensory cues such as a certain smell or visual landmark. Pattern separation helps us use cues such as the presence of a particular tree or cars nearby, for example, to distinguish which parking space we chose today, as opposed to yesterday or the day before. This ability appears to be particularly diminished in people with anxiety and mood disorders. Scientists can produce deficits in pattern separation in animals by blocking neurogenesis, using x-ray radiation to kill targeted populations of cells in the dentate gyrus. Because such studies have not established the precise identity of which cells are being recorded from, however, no one has been able to address the “burning question” in the field: "how young, adult-born neurons and mature dentate granule neurons differ in their activity," says Amar Sahay, a neuroscientist at the Massachusetts General Hospital and Harvard Medical School. © 2016 American Association for the Advancement of Scienc
How is the brain able to use past experiences to guide decision-making? A few years ago, researchers supported by the National Institutes of Health discovered in rats that awake mental replay of past experiences is critical for learning and making informed choices. Now, the team has discovered key secrets of the underlying brain circuitry – including a unique system that encodes location during inactive periods. “Advances such as these in understanding cellular and circuit-level processes underlying such basic functions as executive function, social cognition, and memory fit into NIMH’s mission of discovering the roots of complex behaviors,” said NIMH acting director Bruce Cuthbert, Ph.D. While a rat is moving through a maze — or just mentally replaying the experience — an area in the brain’s memory hub, or hippocampus, specialized for locations, called CA1, communicates with a decision-making area in the executive hub or prefrontal cortex (PFC). A distinct subset of PFC neurons excited during mental replay of the experience are activated during movement, while another distinct subset, less engaged during movement in the maze – and therefore potentially distracting – are inhibited during replay. “Such strongly coordinated activity within this CA1-PFC circuit during awake replay is likely to optimize the brain’s ability to consolidate memories and use them to decide on future action” explained Shantanu Jadhav, Ph.D. (link is external), now an assistant professor at Brandeis University, Waltham, MA., the study’s co-first author. His contributions to this line of research were made possible, in part, by a Pathway to Independence award from the Office of Research Training and Career Development of the NIH’s National Institute of Mental Health (NIMH).
By Kj Dell’Antonia New research shows that the youngest students in a classroom are more likely to be given a diagnosis of attention deficit hyperactivity disorder than the oldest. The findings raise questions about how we regard those wiggly children who just can’t seem to sit still – and who also happen to be the youngest in their class. Researchers in Taiwan looked at data from 378,881 children ages 4 to 17 and found that students born in August, the cut-off month for school entry in that country, were more likely to be given diagnoses of A.D.H.D. than students born in September. The children born in September would have missed the previous year’s cut-off date for school entry, and thus had nearly a full extra year to mature before entering school. The findings were published Thursday in The Journal of Pediatrics. While few dispute that A.D.H.D. is a legitimate disability that can impede a child’s personal and school success and that treatment can be effective, “our findings emphasize the importance of considering the age of a child within a grade when diagnosing A.D.H.D. and prescribing medication for treating A.D.H.D.,” the authors concluded. Dr. Mu-Hong Chen, a member of the department of psychiatry at Taipei Veterans General Hospital in Taiwan and the lead author of the study, hopes that a better understanding of the data linking relative age at school entry to an A.D.H.D. diagnosis will encourage parents, teachers and clinicians to give the youngest children in a grade enough time and help to allow them to prove their ability. Other research has shown similar results. An earlier study in the United States, for example, found that roughly 8.4 percent of children born in the month before their state’s cutoff date for kindergarten eligibility are given A.D.H.D. diagnoses, compared to 5.1 percent of children born in the month immediately afterward. © 2016 The New York Times Company
By Dominic Howell BBC News Gum disease has been linked to a greater rate of cognitive decline in people with Alzheimer's disease, early stage research has suggested. The small study, published in PLOS ONE, looked at 59 people who were all deemed to have mild to moderate dementia. It is thought the body's response to gum inflammation may be hastening the brain's decline. The Alzheimer's Society said if the link was proven to be true, then good oral health may help slow dementia. The body's response to inflammatory conditions was cited as a possible reason for the quicker decline. Inflammation causes immune cells to swell and has long been associated with Alzheimer's. Researchers believe their findings add weight to evidence that inflammation in the brain is what drives the disease. 'Six-fold increase' The study, jointly led by the University of Southampton and King's College London, cognitively assessed the participants, and took blood samples to measure inflammatory markers in their blood. Their oral health was also assessed by a dental hygienist who was unaware of the cognitive outcomes. Of the sample group, 22 were found to have considerable gum disease while for the remaining 37 patients the disease was much less apparent. The average age of the group with gum disease was 75, and in the other group it was 79. A majority of participants - 52 - were followed up at six months, and all assessments were repeated. The presence of gum disease - or periodontitis as it is known - was associated with a six-fold increase in the rate of cognitive decline, the study suggested. © 2016 BBC
Link ID: 21976 - Posted: 03.12.2016
Susan Gaidos Most people would be happy to get rid of excess body fat. Even better: Trade the spare tire for something useful — say, better-functioning knees or hips, or a fix for an ailing heart or a broken bone. The idea is not far-fetched, some scientists say. Researchers worldwide are repurposing discarded fat to repair body parts damaged by injury, disease or age. Recent studies in lab animals and humans show that the much-maligned material can be a source of cells useful for treating a wide range of ills. At the University of Pittsburgh, bioengineer Rocky Tuan and colleagues extract buckets full of yellow fat from volunteers’ bellies and thighs and turn the liposuctioned material into tissue that resembles shock-absorbing cartilage. If the cartilage works as well in people as it has in animals, Tuan’s approach might someday offer a kind of self-repair for osteoarthritis, the painful degeneration of cartilage in the joints. He’s also using fat cells to grow replacement parts for the tendons and ligaments that support the joints. Foremost among fat’s virtues is its richness of stem cells, which have the ability to divide and grow into a wide variety of tissue types. Fat stem cells — also known as adipose-derived stem cells — can be coerced to grow into bone, cartilage, muscle tissue or, of course, more fat. Cells from fat are being tested to mend tissues found in damaged joints, hearts and muscle, and to regrow bone and heal wounds. © Society for Science & the Public 2000 - 2016
Rich Stanton In 1976, the driving simulation Death Race was removed from an Illinois amusement park. There had, according to a news story at the time, been complaints that it encouraged players to run over pedestrians to score points. Through a series of subsequent newspaper reports, the US National Safety Council labelled the game “gross” and motoring groups demanded its removal from distribution. The first moral panic over video game violence had begun. This January, a group of four scholars published a paper analysing the links between playing violent video games at a young age and aggressive behaviour in later life. The titles mentioned in the report are around 15-years-old – one of several troubling ambiguities to be found in the research. Nevertheless, the quality and quantity of the data make this an uncommonly valuable study. Given that game violence remains a favoured bogeyman for politicians, press and pressure groups, it should be shocking that such a robust study of the phenomenon is rare. But it is, and it’s important to ask why. A history of violence With the arrival of Pong in 1973, video games became a commercial reality, but now, in 2016, they are still on the rocky path to mass acceptance that all new media must traverse. The truth is that the big targets of moral concern – Doom, Grand Theft Auto, Call of Duty – are undeniably about killing and they are undeniably popular among male teenagers. An industry report estimates that 80% of the audience for the Call of Duty series is male, and 21% is aged 10-14. Going by the 18 rating on the last three entries, that means at least a fifth of the game’s vast audience shouldn’t be playing. © 2016 Guardian News and Media Limited
By GINA KOLATA Marty and Matt Reiswig, two brothers in Denver, knew that Alzheimer’s disease ran in their family, but neither of them understood why. Then a cousin, Gary Reiswig, whom they barely knew, wrote a book about their family, “The Thousand Mile Stare.” When the brothers read it, they realized what they were facing. In the extended Reiswig family, Alzheimer’s disease is not just a random occurrence. It results from a mutated gene that is passed down from parent to child. If you inherit the mutated gene, Alzheimer’s will emerge at around age 50 — with absolute certainty. Your child has a 50-50 chance of suffering the same fate. The revelation came as a shock. And so did the next one: The brothers learned that there is a blood test that can reveal whether one carries the mutated gene. They could decide to know if they had it. Or not. It’s a dilemma more people are facing as scientists discover more genetic mutations linked to diseases. Often the newly discovered gene increases risk, but does not guarantee it. Sometimes knowing can be useful: If you have a gene mutation that makes colon cancer much more likely , for example, then frequent colonoscopies may help doctors stave off trouble. But then there are genes that make a dreaded disease a certainty: There is no way to prevent it, and no way to treat it. Marty Reiswig, 37, saw his father, now in the final stages of Alzheimer’s, slowly lose his ability to think, to remember, to care for himself, or even to recognize his wife and sons. Mr. Reiswig knows that if he has the gene, he has perhaps a bit more than a decade before the first symptoms appear. If he has it, his two young children may have it, too. He wavers about getting tested. © 2016 The New York Times Company
By Roberto A. Ferdman In the mid 1970s, psychologist Merrill Elias began tracking the cognitive abilities of more than a thousand people in the state of New York. The goal was fairly specific: to observe the relationship between people's blood pressure and brain performance. And for decades he did just that, eventually expanding the Maine-Syracuse Longitudinal Study (MSLS) to observe other cardiovascular risk factors, including diabetes, obesity, and smoking. There was never an inkling that his research would lead to any sort of discovery about chocolate. And yet, 40 years later, it seems to have done just that. Late in the study, Elias and his team had an idea. Why not ask the participants what they were eating too? It wasn't unreasonable to wonder if what someone ate might add to the discussion. Diets, after all, had been shown to affect the risk factors Elias was already monitoring. Plus, they had this large pool of participants at their disposal, a perfect chance to learn a bit more about the decisions people were making about food. The researchers incorporated a new questionnaire into the sixth wave of their data collection, which spanned the five years between 2001 and 2006 (there have been seven waves in all, each conducted in five year intervals). The questionnaire gathered all sorts of information about the dietary habits of the participants. And the dietary habits of the participants revealed an interesting pattern. "We found that people who eat chocolate at least once a week tend to perform better cognitively," said Elias. "It's significant—it touches a number of cognitive domains." © 1996-2016 The Washington Post
By DONALD G. McNEIL Jr. and CATHERINE SAINT LOUIS The Zika virus damages many fetuses carried by infected and symptomatic mothers, regardless of when in pregnancy the infection occurs, according to a small but frightening study released on Friday by Brazilian and American researchers. In a separate report published on Friday, other scientists suggested a mechanism for the damage, showing in laboratory experiments that the virus targets and destroys fetal cells that eventually form the brain’s cortex. The reports are far from conclusive, but the studies help shed light on a mysterious epidemic that has swept across more than two dozen countries in the Western Hemisphere, alarming citizens and unnerving public health officials. In the first study, published in The New England Journal of Medicine, researchers found that 29 percent of women who had ultrasound examinations after testing positive for infection with the Zika virus had fetuses that suffered “grave outcomes.” They included fetal death, tiny heads, shrunken placentas and nerve damage that suggested blindness. “This is going to have a chilling effect,” said Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases. “Now there’s almost no doubt that Zika is the cause.” The small size of the study, which looked at 88 women at one clinic in Rio de Janeiro, was a limitation, Dr. Fauci added. From such a small sample, it is impossible to be certain how often fetal damage may occur in a much larger population. © 2016 The New York Times Company
Keyword: Development of the Brain
Link ID: 21957 - Posted: 03.05.2016
Mo Costandi Most of us are well aware of the health risks associated with obesity. Being overweight or obese is associated with an increased risk of numerous other conditions, from high blood pressure, heart disease and stroke, to diabetes, gout and some forms of cancer. Self-control saps memory resources Read more Research published over the past few years shows that obesity also has neurological consequences – it is associated with altered function in, and shrinkage of, certain parts of the brain, particularly the frontal lobes, which are the seat of intelligence, and the hippocampus, which is critical for memory formation. A new study now shows that this in turn is associated with impaired memory function. Lucy Cheke of the University of Cambridge and her colleagues recruited 50 volunteers aged between 18 and 35, with Body Mass Indexes (BMIs) ranging from 18 (underweight) to 51 (extremely obese), and asked them to perform a computerised memory test called the “Treasure Hunt Task”. This involved moving food items around around complex scenes, such as a desert with palm trees, hiding them in various locations, and indicating afterwards where they had hidden them. The participants were then shown various locations from the computerised scenes, and some of the food items, and asked if they had hidden something in each of the locations, or where they had hidden each of the items. Finally, they were shown pairs of the food items they had seen, and asked to indicate which of each pair they had hidden first. © 2016 Guardian News and Media Limited
By Gretchen Reynolds Learning in midlife to juggle, swim, ride a bicycle or, in my case, snowboard could change and strengthen the brain in ways that practicing other familiar pursuits such as crossword puzzles or marathon training will not, according to an accumulating body of research about the unique impacts of motor learning on the brain. When most of us consider learning and intelligence, we think of activities such as adding numbers, remembering names, writing poetry, learning a new language. Such complex thinking generally is classified as “higher-order” cognition and results in activity within certain portions of the brain and promotes plasticity, or physical changes, in those areas. There is strong evidence that learning a second language as an adult, for instance, results in increased white matter in the parts of the brain known to be involved in language processing. Regular exercise likewise changes the brain, as I frequently have written, with studies in animals showing that running and other types of physical activities increase the number of new brain cells created in parts of the brain that are integral to memory and thinking. But the impacts of learning on one of the most primal portions of the brain have been surprisingly underappreciated, both scientifically and outside the lab. Most of us pay little attention to our motor cortex, which controls how well we can move. “We have a tendency to admire motor skills,” said Dr. John Krakauer, a professor of neurology and director of the Center for the Study of Motor Learning and Brain Repair at Johns Hopkins University in Baltimore. We like watching athletes in action, he said. But most of us make little effort to hone our motor skills in adulthood, and very few of us try to expand them by, for instance, learning a new sport. We could be short-changing our brains. © 2016 The New York Times Company
By Jonathan Webb Science reporter, BBC News Three British researchers have won a prize worth one million euros, awarded each year for an "outstanding contribution to European neuroscience". Tim Bliss, Graham Collingridge and Richard Morris revealed how strengthened connections between brain cells can store our memories. Our present understanding of memory is built on their work, which unpicked the mechanisms and molecules involved. This is the first time the Brain Prize has been won by an entirely UK team. It is awarded by a Danish charitable foundation and the 2016 winners were announced in London on Tuesday. Speaking to journalists at a media conference, Prof Morris explained it was the "chemistry of memory" that he and his colleagues had managed to illuminate. Fire together, wire together "Before this team got going, we had some idea about particular areas of the brain that might be involved in memory… but what we didn't have was any real understanding of how it worked," explained the professor, who works at the University of Edinburgh. The "team" of three winners never worked together in the same laboratory, but they have collaborated over the years. "Memories change the brain - the brain is plastic," said Prof Bliss, who worked for many years at the National Institute of Medical Research in London and is now affiliated with the Francis Crick Institute. Those changes occur at the junctions between nerve cells - synapses - and were described in a pioneering study by Bliss and a Norwegian colleague, Terje Lømo, in the 1970s. © 2016 BBC.
Keyword: Learning & Memory
Link ID: 21947 - Posted: 03.03.2016
Ewan Birney The Daily Mail recently ran an article about how alcohol abuse could harm future generations, via the (exciting-sounding) mechanism of trans-generational epigenetics. This is an emotive topic, combining a commonplace habit (drinking beer and wine) with a scary outcome (harming your children, grandchildren and future generations) and adding a twist of science for gravitas. It’s not surprising that this research has been handed a megaphone by the mainstream press – but does the science stack up? To start with, the research was carried out in rats, as multi-generational experiments on humans are both grossly unethical and logistically extremely hard. This crucial bit of information is missing from both the Daily Mail headline and the paper’s title. Secondly, the big effects of alcohol consumption were mainly seen on the rats’ children and grandchildren – the effects on their great grandchildren were smaller. That is really important, because if there’s no effect on great grandchildren, it’s probably not due to epigenetics. Drinking large amounts of alcohol (for a rat) whilst pregnant would be expected to have an effect on the children and even the grandchildren. This is because the eggs of female mammals are made early on in foetal development, whilst a daughter is developing in the womb. So if that cell (the egg) also gives rise to a daughter, she will have directly experienced exposures that occurred during her maternal grandmother’s pregnancy. © 2016 Guardian News and Media Limited or its affiliated companies.
By James Gallagher Health editor, BBC News website People who are obese have a worse memory than their thinner friends, a small study shows. Tests on 50 people showed being overweight was linked to worse "episodic memory" or the ability to remember past experiences. The study in the Quarterly Journal of Experimental Psychology argues that a less vivid memory of recent meals may lead to overeating. However, other aspects of memory - such as general knowledge - were unaffected. Tests on rats have previously shown that with burgeoning waistlines come poorer performances in memory tests, but the evidence in humans has been mixed. The latest experiments looked at episodic memory - the video tape in your mind - that remembers the smell of a cup of coffee or the feel of holding someone's hand. Fifty people with a Body Mass Index (BMI) ranging from 18 (healthy) to 51 (very obese) took part in a memory test - a bit like doing a treasure hunt on your own. They had to "hide" objects at different times and on different scenes displayed on a computer screen. They were later asked to recall what they had hidden, when and where. The results showed obese people's scores were 15% lower than thinner people. Dr Lucy Cheke, from the University of Cambridge, told the BBC News website: "The suggestion we're making is that a higher BMI is having some reduction on the vividness of memory, but they're not drawing blanks and having amnesia. "But if they have a less strong memory of a recent meal, with a less strong impact in the mind, then they may have less ability to regulate how much they eat later on." Hunger hormones play a huge role in how much we eat, but it is already recognised that our minds have a key role too. © 2016 BBC
Keyword: Learning & Memory
Link ID: 21933 - Posted: 02.27.2016
The dodo is an extinct flightless bird whose name has become synonymous with stupidity. But it turns out that the dodo was no bird brain, but instead a reasonably brainy bird. Scientists said on Wednesday they figured out the dodo's brain size and structure based on an analysis of a well-preserved skull from a museum collection. They determined its brain was not unusually small but rather completely in proportion to its body size. They also found the dodo may have had a better sense of smell than most birds, with an enlarged olfactory region of the brain. This trait, unusual for birds, probably let it sniff out ripe fruit to eat. The research suggests the dodo, rather than being stupid, boasted at least the same intelligence as its fellow members of the pigeon and dove family. Mauritius Dodo bird A skeleton of a Mauritius Dodo bird stands at an exhibition in the Mauritius Institute Museum in Port Louis in this Dec. 27, 2005 file photo. (Reuters) "If we take brain size — or rather, volume, as we measured here — as a proxy for intelligence, then the dodo was as smart as a common pigeon," paleontologist Eugenia Gold of Stony Brook University in New York state said. "Common pigeons are actually smarter than they get credit for, as they were trained as message carriers during the world wars." ©2016 CBC/Radio-Canada.
by Giuseppe Gangarossa When we think about sex hormones, notably estrogens and androgens, we usually associate them with sex, gender and body development. Like all hormones, they are chemical messengers, substances produced in one part of the body that go on to tell other parts what to do. However, we often have the tendency to forget the enormous impact that these steroid hormones have on brain functions. From animal studies, it has become clear that during early development, exposure of the brain to testosterone and estradiol, hormones present in both males and females, leads to irreversible changes in the nervous system (McCarthy et al., 2012). A growing and very appealing body of science suggests that sex hormones play a neuromodulatory role in cognitive brain function (Janowsky, 2006). Moreover, testosterone dysfunctions (hypogonadism, chemical castration, etc.) have shown to be associated with memory defects. However, in spite of these advances, it still remains an enigma how sex hormones affect the brain. In an interesting paper published in PLOS ONE, Picot and colleagues tried to fill in one piece of the puzzle. They investigated the neurobiological effects of cerebral androgen receptor (AR) ablation on hippocampal plasticity and cognitive performance in male rodents (Picot et al., 2016). Although several reports have already highlighted a link between sex hormones and cognitive function (Galea et al., 2008; Janowsky, 2006), much more needs to be done to fully elucidate the “non-sexual” functions of androgens.
By Meeri Kim Teenagers tend to have a bad reputation in our society, and perhaps rightly so. When compared to children or adults, adolescents are more likely to engage in binge drinking, drug use, unprotected sex, criminal activity, and reckless driving. Risk-taking is like second nature to youth of a certain age, leading health experts to cite preventable and self-inflicted causes as the biggest threats to adolescent well-being in industrialized societies. But before going off on a tirade about groups of reckless young hooligans, consider that a recent study may have revealed a silver lining to all that misbehavior. While adolescents will take more risks in the presence of their peers than when alone, it turns out that peers can also encourage them to learn faster and engage in more exploratory acts. A group of 101 late adolescent males were randomly assigned to play the Iowa Gambling Task, a psychological game used to assess decision making, either alone or observed by their peers. The task involves four decks of cards: two are “lucky” decks that will generate long-term gain if the player continues to draw from them, while the other two are “unlucky” decks that have the opposite effect. The player chooses to play or pass cards drawn from one of these decks, eventually catching on to which of the decks are lucky or unlucky — and subsequently only playing from the lucky ones.
Laura Sanders In a multivirus competition, a newcomer came out on top for its ability to transport genetic cargo to a mouse’s brain cells. The engineered virus AAV-PHP.B was best at delivering a gene that instructed Purkinje cells, the dots in the micrograph above, to take on a whitish glow. Unaffected surrounding cells in the mouse cerebellum look blue. Cargo carried by viruses like AAV-PHP.B could one day replace faulty genes in the brains of people. AAV-PHP.B beat out other viruses including a similar one called AAV9, which is already used to get genes into the brains of mice. Genes delivered by AAV-PHP.B also showed up in the spinal cord, retina and elsewhere in the body, Benjamin Deverman of Caltech and colleagues report in the February Nature Biotechnology. Similar competitions could uncover viruses with the ability to deliver genes to specific types of cells, the researchers write. Selective viruses that can also get into the brain would enable deeper studies of the brain and might improve gene therapy techniques in people. © Society for Science & the Public 2000 - 2016
By DONALD G. McNEIL Jr. A baby with a shrunken, misshapen head is surely a heartbreaking sight. But reproductive health experts are warning that microcephaly may be only the most obvious consequence of the spread of the Zika virus. Even infants who appear normal at birth may be at higher risk for mental illnesses later in life if their mothers were infected during pregnancy, many researchers fear. The Zika virus, they say, closely resembles some infectious agents that have been linked to the development of autism, bipolar disorder and schizophrenia. Schizophrenia and other debilitating mental illnesses have no single cause, experts emphasized in interviews. The conditions are thought to arise from a combination of factors, including genetic predisposition and traumas later in life, such as sexual or physical abuse, abandonment or heavy drug use. But illnesses in utero, including viral infections, are thought to be a trigger. “The consequences of this go way beyond microcephaly,” said Dr. W. Ian Lipkin, who directs The Center for Infection and Immunity at Columbia University. Here is a look at the most prominent rumors and theories about Zika virus, along with responses from scientists. Among children in Latin America and the Caribbean, “I wouldn’t be surprised if we saw a big upswing in A.D.H.D., autism, epilepsy and schizophrenia,” he added. “We’re looking at a large group of individuals who may not be able to function in the world.” © 2016 The New York Times Company